U.S. Pat. No. 5,267,583 entitled "Multiple-fold Automatic Umbrella Controlled by Single Push Button" issued to the same inventor of the co-inventors of this application disclosed an automatic umbrella having a push button which may be depressed to open and close the umbrella. However, the structure of the control means and the relevant elements are complex and inconveniently operated, thereby requiring a simplification and modification for improving their mechanism and operation.
The conventional joints for the ribs of an automatic umbrella (prior arts) as shown in FIGS. 12-15 are not strong enough to resist a strong wind or external force, easily damaging the ribs.
As shown in FIGS. 12, 13, a conventional joint member 27 is provided for connecting the rear rib 26, the resilient rib 25a and the middle rib 25, having a front bifurcated fork 270 for pivotally connecting an outer end of the resilient rib 25a, and having a pressed outer end 252 of the middle rib 25 pivotally connected with a pair of lugs 271. Since, the lugs 271 of the joint 27 are not long enough to embed or "clamp" the outer end 252 of the middle rib 25 within the joint 27, the front fork 270 as connected with the resilient rod 25a may be twisted either rightwardly or leftwardly when subjected to a strong wind force, easily deforming and damaging the umbrella ribs.
As shown in FIGS. 14, 15, a pair of outer fork ends 222 of the top rib 22 having a U-shaped cross section is not reinforced with any packing or retainer between the two fork ends 222, thereby being easily deformed and damaged to influence the smooth operation of the umbrella and to shorten the service life of the umbrella.
The present inventors have found the drawbacks of the conventional automatic umbrella and invented the present umbrella with simplified mechanism and reinforced ribs.